Abstract: The present invention provides a converter including a plurality of sub-modules connected in series to each other, wherein each of the sub-modules includes a first half-bridge unit including a first energy storage unit, and a plurality of first power semiconductors connected in parallel to the first energy storage unit and connected in series to each other; a second half-bridge unit including a second energy storage unit, and a plurality of second power semiconductors connected in parallel to the second energy storage unit and connected in series to each other; and an auxiliary circuit unit connecting the first half-bridge unit and the second half-bridge unit; wherein the auxiliary circuit unit includes a single third power semiconductor and a single diode.